Epidemiological studies report a link between short sleep duration and hypertension, and there is evidence to suggest this relationship might be stronger in women when compared to men. Recent work from our laboratory demonstrates that total sleep deprivation (TSD) elicits divergent sympathetic neural responses in young men and women. Despite the heightened risk of cardiovascular disease associated with aging, the relations between sleep deprivation, sympathetic neural activity, and arterial blood pressure remain confined to young, healthy individuals. The proposed project will comprehensively examine sympathetic neural and cardiovascular responses to TSD in older humans, including postmenopausal women. The project includes three specific aims. Aim 1 will determine if TSD alters arterial blood pressure and sympathetic neural activity in postmenopausal women. Aim 2 will determine if TSD alters neural cardiovascular reactivity to acute laboratory stressors in postmenopausal women. Aim 3 is specific to the Academic Research Enhancement Award (R15) mission, and will provide undergraduate and graduate students from our institution an opportunity to fully engage in biomedical research related to sleep and cardiovascular physiology. Our central hypothesis is that TSD will elicit acute hypertension and sympathetic overactivity in older humans, and that this neural cardiovascular dysfunction will be most dramatic in postmenopausal women. We will employ a novel experimental approach (randomized, crossover design; TSD vs. normal sleep) that includes the gold-standard analysis of sympathetic neural activity via microneurography and integrative analysis with other key cardiovascular variables. The proposed research will compliment recent epidemiological and observational studies by providing important mechanistic insight regarding the influence of sleep deprivation on sympathetic neural control in older adults. Moreover, this project addresses three priority areas outlined in the most recent NIH Sleep Disorders Research Plan.